Micronutrients are key elements in plant growth and development. Deficiencies of Ca, Zn, Fe and B have been increasing in some fruit crops. Some reasons are higher crop yields which increase plant nutrient demands, use of high analyses NPK fertilizers containing lower quantities of micro-nutrient contaminants and decreased use of farmyard manure on many agricultural soils. The combined foliar application of Ca, Zn, Fe and B as a source of calcium nitrate 1000mg/l + borax 30mg/l + zinc sulphate 200 mg/l + ferrous sulphate 200 mg/l was favorable to influenced the plant growth characters, physiological attributes, yield as well as quality of papaya. Moreover, the application of borax individually at 30mg/l was showed the earliness in flowering when apply at 60, 90 and 120 days after planting of papaya cv. Taiwan Red Lady. Это и многое другое вы найдете в книге Effect of Foliar Application of Ca, Zn, Fe and B on Papaya (Pankaj P. Bhalerao and B. N. Patel)